1. Field
The present disclosure relates to a cooling system for cooling a nuclear reactor containment structure in the event of a severe accident, and more particularly, to a cooling system of a nuclear reactor containment structure, capable of being driven for a long time by natural convection without supply of power.
2. Discussion of Related Art
In order to prevent damage of a containment building housing a nuclear reactor due to an increase in pressure of the containment building and a large leakage of fission products due to the damage when a severe accident occurs in the nuclear reactor, the containment building includes a release port installed thereto and a filtered exhaust apparatus which condenses and removes water vapor and fission products generated in the nuclear reactor.
Since such a filtered exhaust apparatus, however, has to continuously condense vapor, which continues to be generated in a containment vessel, in a vessel outside the containment vessel, the vessel should significantly increase in size in order to increase operating hours of the filtered exhaust apparatus without an operator's intervention. Currently, the operating hours of the filtered exhaust apparatus is approximately one day. However, it is identified that power restoration of the filtered exhaust apparatus may take a long time after the Fukushima nuclear accident. Therefore, in order to prepare for this situation, there is a need for a filtered exhaust apparatus which may be driven for more than 72 hours without supply of power.
In addition, when the filtered exhaust apparatus is driven for a long time, condensed water within an exhaust apparatus has an increasing temperature and a filter has an increasing temperature due to fission products accumulated in the filter, thereby rapidly deteriorating removal performance of fission products required for the filter.
Meanwhile, since the conventional systems for condensing and filtering vapor cause undesired water hammer by releasing vapor into an overcooled water tank in an initial operation of the filtered exhaust apparatus, pipes and devices related thereto may be damaged.
Consequently, there is a need for methods to solve the above problems.